Tile is an excellent floor covering. It is very durable and generally easy to clean. However, tile is also extremely brittle. Therefore, when it is positioned on a floor it must have a subsurface that does not flex. This can be, for example, a concrete surface or a cementitious underlayment such as Wonderboard™. Materials such as wood, including plywood and particle board are generally unacceptable.
Outdoor applications have additional concerns because of the temperature variations, as well as the effects of water during these temperature variations. Wood is unacceptable in these applications as well as cementitious substrates.
Cement will function as an exterior tile support surface, but it obviously cannot be used in all applications. These problems also exist with a terrazzo floor.